If you have issues with your post and mail being tampered with, you might want to consider a secure post box. More robustly built than a standard letterbox, these models are much more difficult to force open. Some feature 3 point locking systems or have been reinforced against drill attacks. Their slots are secured by an anti-fishing plate, meaning post cannot be removed except by unlocking the door. If your house is unattended for long periods or your post has been tampered with in the past, a secure post box is a wise investment.